Maternal Calcium Intake and Fetal Myocardial Performance: Prospective Mid-Gestation Echocardiography Findings Based on Questionnaire-Derived Dietary Calcium Assessment.

To investigate whether maternal dietary calcium intake during early pregnancy is associated with fetal cardiac function at mid-gestation, given the heightened dependence of the fetal myocardium on extracellular calcium and the lack of previous studies addressing this relationship. This prospective observational study was conducted at Kastamonu Training and Research Hospital between August and November 2025. Pregnant individuals undergoing routine fetal anomaly screening were recruited. Maternal calcium intake over the preceding 3 months was quantified through a calcium-specific food frequency questionnaire. Fetal echocardiography was performed between 18 and 22 weeks of gestation by a single experienced operator. Left and right ventricular myocardial performance indices (MPI), isovolumic intervals, ejection times, E/A ratios, and cardiac morphometrics were measured. Continuous variables were analyzed using Spearman correlation and Mann-Whitney U tests, with significance defined as p < 0.05. A total of 147 participants were analyzed. Maternal calcium intake showed no significant correlations with any fetal cardiac functional parameter, including LV-IVRT (r = -0.035), LV-IVCT (r = -0.058), LV-ET (r = 0.087), MV-TEI (r = -0.102), RV-TEI (r = 0.000), or ventricular filling indices. Categorization by intake < 800 mg/day versus ≥ 800 mg/day similarly revealed no differences in systolic, diastolic, or global cardiac function (all p > 0.13). Dairy products constituted 68.6% of total calcium intake. No statistically significant association was identified between maternal total calcium intake and fetal cardiac function at mid-gestation in this cohort. However, the study may not have been sufficiently powered to exclude small differences in myocardial performance indices. In addition, the absence of an observed association may reflect physiological placental buffering of maternal calcium homeostasis or a temporal mismatch between the period of calcium exposure assessment and fetal functional evaluation. Future studies involving populations with low habitual calcium intake and incorporating biochemical markers are warranted.